It is common for emergency vehicles, repair vehicles, tow trucks, taxis and the like to have mounted lights to warn or advise other motorists and pedestrians of their presence. Typically, these lights are powered by the electrical system of the vehicle through wires which extend from the vehicle electrical system upward through the vehicle roof to the light assembly. Furthermore, in many of these commercially available light units, those component parts which most often require replacement, i.e. the internal electronics and the light bulbs, are attached to the light unit in a manner that their replacement requires removal of the entire light unit from the vehicle. Since typically the base portion of the light unit is fixedly mounted to the vehicle, and the internal electronics are hard wired to the vehicle's electrical system, the replacement of these component parts in conventional commercial light units is time consuming and costly. For example, often these repairs must be done at a repair facility resulting in loss of use of the vehicle until the repair is completed. Furthermore, since the component parts are not readily replaceable, extra light units are often maintained as backups in the event of a failure of one or more component parts. Thus, instead of replacing the component part, the failed light assembly is replaced by the off-the-shelf light unit. In an operation such as a city police force or a utility company, which maintains a large fleet of emergency vehicles, this requirement to maintain a number of spare light units can be quite costly.
Conventional replaceable vehicle light units have been disclosed in U.S. Pat. No. 2,688,688 by Holtz; U.S. Pat. No. 2,825,799 by Julien; and U.S. Pat. No. 3,900,725 by Komon. In Holtz, there is disclosed a replaceable lamp unit for a vehicle which includes a pair of laterally extending electrically conductive fingers which are connected to the vehicle in electrical communication with the vehicle power supply. These fingers are releasably engaged by a complementary pair of laterally extending electrically conductive fingers which are part of the lamp unit so that power can be transmitted between the vehicle and the lamp. On the other hand, Julien discloses a pair of U-shaped resilient connectors which are attached to a light unit and which resiliently engage an upstanding stud which is connected to a base. The base in turn is affixed to the vehicle in a manner that power supply leads from the vehicle electrical system are connected to the upstanding studs for transmitting electrical power to the light unit. Furthermore, in Komon, there is disclosed a navigation light for a boat including a lamp unit which has a lower flange with two female electrically conductive receptacles which slidably engage a pair of upstanding male electrically conductive upstanding members which are attached to a base unit mounted to the boat.
Other conventional light units include U.S. Pat. No. 4,547,840 by Tinder which discloses a holder for mounting a light to a circuit board and which includes a pair of downwardly extending prongs which are engaged within vertical openings in the circuit board. In addition, U.S. Pat. No. 4,415,957 by Schwartz and U.S. Pat. No. 3,530,287 by Husby disclose replaceable lamp units which are removably mounted to a fixedly mounted base.
The Assignee of the present invention has manufactured conventional vehicle light units including a Warn-A-Lite Strobe Model 651 which includes a transparent cover removably mounted to a base having a horizontal upper planar portion and a downwardly depending cylindrical sidewall. A flash tube is mounted to a vertical printed circuit card extending upwardly through a slot in the horizontal upper planar portion. The power supply is mounted to a horizontal printed circuit board which is attached to the base and is hard wired to the vehicle power supply. Removal of the light power supply requires that the base be removed from the vehicle and the connection to the vehicle power supply be severed.